Plug-in hose, couplings are attachment fittings which are also referred to as quick-action plug-in connections.
These plug-in hose couplings are used primarily in low-pressure systems wherein plastic tubes or hoses are often provided for conveying fluid.
Below, for simplification, the term “tube” is also used for hoses.
The plug-in hose couplings afford the advantage that the tube can be fixedly connected to the plug-in hose coupling by simple insertion into the receiving bore.
This leads to a considerable simplification of assembly, which is important primarily in vehicle assembly.
The fixing of the tube in the plug-in hose coupling is brought about by an integrated holding element which is radially resilient.
In the plug-in hose couplings, the resilient holding element is often embodied either as a plate-spring-like, closed or open toothed disc ring or as a slotted lock washer with one or more cutters.
As the tube is passed through, the annular holding element is firstly slightly opened, so that it lies with a slight radial contact pressure around the outer surface of the tube.
This takes place relatively easily since the annular holding element is usually conically beveled or widened in the plug-in direction. The widening can also take plate by means of a pilot ring which is arranged in front of the tube end and is provided with an insertion cone.
When the tube is pulled back, the cutters or teeth then dig into the outer surface of the tube and prevent the tube from being pulled back further.
In the case of a slotted, correspondingly conically formed lock washer, a conical support face is necessary for this purpose, against which the lock washer is supported with its outer face and whose conicity is arranged such that the diameter of the lock washer is reduced in the pulling-out direction of the tube. In this way, the holding force of the lock washer is increased with increasing pulling-out force.
Attachment fittings of the above type are known, for example, from DE 39 23 579 A1, DE 9208519 U1 or DE 43 00 004 A1, with DE 39 23 579 A1 disclosing a system with a toothed disc or lock washer, and with DE 9208519 U1 and DE 43 00 004 A1 disclosing a system with a lock washer.
In the plug-in hose couplings described, the parts, such as seals, conical support rings and holding rings or lock washers are arranged in a predetermined sequence in the throughflow bore of the housing and are fixedly held in position by rolling in or flanging the wall of the housing in the throughflow bore.
A disadvantage of all of these solutions is that, for holding all of the parts required for sealing and for fixing the tube in the plug-in hose coupling in the housing, a relatively long bore, and when using a slotted lock washer, an additional wedge element, are required.
As a result, firstly the production and handling of the housing blanks is complex, and secondly the assembly with an additional component, the wedge element, is also encumbered.